Purification and characterization of an alpha-galactosyltransferase from Trypanosoma brucei.
Biochem J
; 338 ( Pt 2): 545-51, 1999 Mar 01.
Article
in En
| MEDLINE
| ID: mdl-10024534
ABSTRACT
A membrane-associated galactosyltransferase from Trypanosoma brucei was purified 34000-fold by affinity chromatography on UDP-hexanolamine-Sepharosetrade mark. Using SDS/PAGE under reducing conditions, the isolated enzyme ran as a relatively broad band with apparent molecular masses of 53 kDa and 52 kDa, indicative of glycosylation and the existence of two isoforms. N-Glycosylation of the enzyme was subsequently confirmed using Western blotting and either specific binding of concanavalin A or peptide-N4-(N-acetylglucosaminyl)asparagine amidase digestion. The de-N-glycosylated enzyme ran with apparent molecular masses of 51 kDa and 50 kDa, indicative of a single N-glycosylation site. The galactosyltransferase exhibited a pH optimum at 7.2 and had a pronounced requirement for Mn2+ ions (KM=2.5 mM) for its action. The transferase activity was independent of the concentration of Triton X-100. The enzyme was capable of transferring galactose from UDP-galactose to a variety of galactose-based acceptors in alpha-glycosidic linkages. The apparent KM values for UDP-galactose and for the preferred acceptor substrate N-acetyl-lactosamine are 46 microM and 4.5 mM respectively. From these results we would like to suggest that the galactosyltransferase functions in the processing of terminal N-acetyl-lactosamine structures of trypanosomal glycoproteins.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Trypanosoma brucei brucei
/
Galactosyltransferases
Limits:
Animals
Language:
En
Journal:
Biochem J
Year:
1999
Document type:
Article
Affiliation country:
Germany